Apple chief executive, Tim Cook (right), talks to a staff member at an Apple store in Beijing during his visit to China. Photograph: Reuters

Apple expects China to overtake the United States as its biggest market, the company's chief executive has told a Chinese government news agency.

"China is currently our second largest market. I believe it will become our first. I believe strongly that it will," the Xinhua news agency quoted Tim Cook as saying in an interview.

The report gave no details of when Cook thought China, already Apple's second-biggest market, might pass the US. Apple spokespeople in China did not immediately respond to a request for comment.

Apple has said sales in China more than doubled in 2010 and 2011, though growth has slowed in the past year.

Apple's iPhones, iPads and other gadgets are popular with China's highest-earning consumers but the country's fast-growing smartphone market is dominated by handsets that run on the rival Google Android system.

Cook was in Beijing to meet Chinese regulators and managers of state-owned China Unicom, the first Chinese carrier to support the iPhone.

Xinhua said Cook did not respond to rumours Apple might be producing a lower-cost iPhone for developing markets such as China.

Apple opened a multistorey flagship store on a prominent corner in Beijing's busy Wangfujing shopping area in October, raising its number of mainland retail outlets to 11. Independent stores also resell Apple products.

According to Xinhua, Cook responded to complaints about wages and other work issues at Foxconn, the Taiwanese company that assembles Apple's products in vast factories in China, by saying his company enforced strict codes of conduct for its suppliers.

"We care very deeply about every worker that touches an Apple product, whether they are making it, selling it, serving it or marketing it. We hold ourselves to a very high standard there," he was quoted as saying.